Sound signal



Dec. 27, 1938. R. M. CRITCHFIELD A SOUND S IGNAL I Filed July 27, 1929Patented Dec. 27, 1938 UNITED STATES PATENT OFFiCE SOUND SIGNAL wareApplication July 27, 1929, Serial No. 381,515

13 Claims.

This invention relates to improvements in sound signalling devicesparticularly adaptable for use on motor vehicles.

It is among the objects of the present invention to provide a soundsignalling device, or

warning instrument, of simple structure and design which may be producedat a minimum expenditure of time and labor.

Another object of this invention is to provide a horn or a signallingdevice which may be adjusted or regulated to vary the quality andintensity of sound produced, without disturbing the adjustment oraffecting the operativeness of the driving motor or any other portion ofthe mechanism.

Another object of the invention is to provide a Warning signal that willbe substantially free of mechanical noise and that will approximate thetone of an air horn. z

Further objects and advantages of the present invention will be apparentfrom the following description, reference being had to the accompanyingdrawing wherein a preferred embodiment of one form of the presentinvention is clearly shown.

In the drawing:

Fig. 1 is an elevation of my sound signal device, with parts thereofbroken away to show the operative mechanism thereof in longitudinalsection, substantially as would appear along the line and in thedirection of the arrows of Fi 2.

Fig. 2 is an end view looking in the direction of arrow 2 of Fig. 1 withthe motor housing in cross section.

Fig. 3 is a sectional view on line 3-3 of Fig. 2.

Fig. 4 is a view of a piston disc illustrating a detail of itsconstruction.

With particular reference to the drawing the numeral 28 designates abase, cup-shaped in form,

upon which is supported the operating mechanism of the horn.. The bottomof the base 28 is termed the main mounting platform 2|. The centralportion of this platform 2| is apertured,

the metal punched out of the bottom to form the aperture being bent upto provide a bracket 22 having a portion 23 substantially parallel withbut spaced from the mounting platform 2 I. An-

other bracket 24 formed from the material punched out of the bottom toform the aperture, provides a bracket diametrically opposite the bracket22. The base 28 is provided with an outwardly extending flange 25 havinga plurality of apertures for receiving screws 26 which pass throughapertures in a flange 21 of a collar 28 to secure said collar to thebase 28. A diaphragm 29 is interposed between the flanges 25 and 21 andis clamped tightly therebetween by means of the screws 26 thus providinga yieldable partition between the collar 28 and the base 20. 5

Upon the parallel portion 23 of the bracket 22 there is secured at oneend a blade spring 30, which extends toward the center of the base andparallel with the main mounting platform 2|, and the circuit controllermechanism of the motor unit is insulatingly mounted upon this bracket insubstantial parallel relation with said blade spring as will presentlyappear. In the present instance the circuit controller mechanismcomprises a leaf spring bracket 3| which provides a nonconducting bufferblock 33 and a movable contact 32 which cooperates with an adjustablecontact 35 carried by a rigid bracket 34 in substantial alignment withthe contact 32. These contact supporting elements are secured to thebracket 23 by screws 36.

To the free end of the blade spring 38 there is secured an angularbracket or stirrup 38 which has an adjustable screw 39 supported in itsfree end, and adapted to engage the insulating member or buffer 33carried on the movable contact arm 3|. Upon movement of the stirrup 38,the blade spring 38 functions to open the circuit between the contacts32 and 35. A rod 40 is secured to the free end of the blade spring 38and extends through the diaphragm 29 and spacing washers 4| and 42.Washers 4| and 42 and diaphragm 29 are clamped against a shoulder 48a ofthe rod 40 by a nut 43 threadedly engaging the rod. The armature rod 40thus terminates within the sound chamber defined by the collar 28,substantially coaxial with the orifice thereof. On this threadedextension 44 of the armature rod there is mounted a piston disc 45 whichis secured in place by a nut 46.

The collar 28 is formed to provide a chamber 58 that embodies theannular plane portion 5| merging into the conical aperture 52, thatleads into the relatively small neck 53 within which is secured themouth 54 of a trumpet 55. Collar 28 may be formed in any preferredmanner, but it is desirable that the portion 5| be finished to a planesurface, though the adjacent surfaces of the piston 45 and portion 5|may be conical and substantially parallel. Thus, the chamber 50 isdefined by the collar member 28 in the appointments just described andthe yieldable partition member or diaphragm 29. In assembled form thearmature rod 48 lies substantially coaxial with th s chamber andsupports the piston 45 in close 55 c of the insert 56.

proximity to the plane portion 5| of the collar 28. In the instantinvention it is desired that a relatively close approach between thedisc 45 and the plane 5| may be obtained, and this is accomplished byproviding the disc 45 with an insert 56 centrally thereof and that hasthreaded engagement with the threaded portion 44 of the armature rod 40.The insert 56 is provided with a flange 5'! on one side of the disc,which flange is notched at equally spaced points as 58 for cooperationwith a special tool or instrument to'aid in turning the insert andconsequently the disc 45 upon the threaded portion of the rod 40. Whenthe disc assembly, as illustrated in Fig. 4, has been threaded upon thearmature rod 46 and adjusted to the proper position, it is securedthereto by the lock nut 46. positioned and proportioned in dimension,that adjustment of the disc 45 relative to the rod 46 may be made eitherbefore the mechanism has been assembled, or after assembly has beencompleted. V

The adjustment is accomplished when the apparatus has been assembled, byinserting a tubular form of the spanner wrench within the trumpet 55 toengage the notches 58 in the flange While holding the wrench inengagement therewith, a socket wrench is then inserted within thetubular spanner wrench to engage the nut 46, by which it is loosenedsufiiciently to allow the desired adjustment of the disc 45 upon thearmature rod 40. When the desired adjustment of the disc 45 relativelyto i the plane 5| has been obtained, the tubular rod and plane, whilethe socket wrench is reinserted to tighten the nut 46 and secure the,disc 45 in the altered position upon the rod 46. Thus,

adjustment of the air gap 60 betweenthe disc 45 and plane portion 5| maybe altered after the sound signal has been mounted upon the vehicle,

and without disturbing any of the other parts of the device.

An armature 65 is carried on the rod 40 adjacent the free end of thespring 36, said armature being maintained in normal position by thetension in the spring 30 and the diaphragm 29. The armature 65 isreciprocated or actuated by means of an electro-magnet device comprisinga field frame 66 which is adjustably supported on the mounting platform2| of the base. The field frame comprises a plurality of E-shapedmagnetic plates 67 riveted together, the E-shaped plates formingparallel grooves 68 and 69 into which a field winding 10 is adapted tobe placed. The end plates H and 12 of the field frame are provided withangular shelf portions 13 and 14 respectively, said portions beingapertured at Hand 76 to permit insertion of the field wlnding 'fll intothe grooves 68 and 69. V The shelf 14 is provided with a centralaperture 11 while the shelf 13 has two such apertures spaced on oppositesides of the center. These apertures 11 are so designed and spaced as tocooperate with threaded studs 18 secured in the mounting platform 2| asillustrated in 'Fig. 2

and each of the threaded studs is provided with a pair of nuts 19 and86, one being disposed each side of the shelf portions 13 and .74. Thenuts 19 and 88 upon the stud 18 provide a means of adjusting andsecuring the field frame 66 in proper relation with respect to themounting platform 2|, it being obvious that the nut 19 may be run up anddown on the stud 18 to determine the These partslare so' armature 7device.

supports the armature 65 in close proximity to the field frame 66 andthat the rod 40 is reciprocably movable through the aperture 85 of thefield frame. When it is deemed that the gap between the armature andfield frame is too great, then the nuts 80 of the studs 18 may be loosedand the spacing nuts 19 thereof run out to properly position the fieldframe 80 again run down as before.

In the operation of this sound signal, energization of the field frameor electro-magnetic unit attracts the armature 65 against the efiect ofand the nuts the spring 36 and the diaphragm 29. The arm'a ture isthereby moved toward the field frame and consequently flexes thediaphragm outwardly toward the trumpet 55 and carries with it the disc45. This movement of the armature will cause the contact carrying member3| to be flexed to open the circuit through the contact points 32 r and35, and permit the spring 36 and diaphragm 29 to return to normalposition again closing the contacts 32 and 35 which reconditions theparts for the above cycle of movement. The disc 45 acts principally inthe capacity of a piston in cooperation with the plane 5| of the collar28. As earlier stated the disc 45 is adjusted so that it is inpreference in close proximity t the plane 5| at the extreme of theelectrically energized movement'of the rod and armature. That is, it isso adjusted with respect to the plane 5| and rod '40 that when the rod40 is at the left hand movement at which the armature is again energized, the'disc is stopped in'its return movement and again drawn towardthe mouth of the trumpet. The effect produced is a delicate pulsation ofsound as the piston sets the air column into vibration and whenimpressed upon-the other vibrations of the horn produces a penetratingwarning signal of pleasing quality.

The area of the gap is such that when the disc 45 is in this extreme ofapproach or near that extreme that the rush of air or fiuid content frombetween the elements 45 and 5| will attain extremely high velocities.The fluid movement will suddenly cease or be terminated by completecutting off or substantial cutting oif thereof due to the close approachof the elements described. By reason of this effect there is 'a rush ofair through the aperture of the chamber 5| at the stated extreme ofeachvibratory stroke of the The sudden stopping of the fluid current'flowingthrough the neck into the trumpet sets the air column into rapidvibration and when contributed to by the sound produced by the diaphragmproduces a sounding signal of very desirable qualities. The toneproduced is remarkably free of mechanical noise and approximates thetone of an air horn so closely as to be barely detectable therefrom.

While I have illustrated the trumpet 55 as of drawn or spun formation, Ido not limit myself to thatparticular form, but may formthe trumpet froma pair of symmetrical stampings which I may secure together by seamingor by welding, or I may cast the trumpet either integral with orseparate from the collar 28.

While the form of embodiment of the present invention as hereindisclosed, constitutes a preferred form, it is to be understood thatother forms might be adopted, all coming Within the scope of the claimswhich follow.

What is claimed is as follows:

1. A signal device comprising in combination; a base; a collar providedwith a wall, said wall provided with an aperture having a conicalportion and a neck portion; a trumpet secured in said neck portion; adiaphragm clamped between said collar and base; a disc extending oversaid conical portion and connected with said diaphragm, said disc lyingin close juxtaposition to the mouth of said conical portion merging withsaid wall substantially at right angles to the axis of said collar; amotor carried by said base; a rod connecting said motor with thediaphragm and disc, said rod having an end extending into said conicalportion; and means for altering the position of said disc relative tosaid wall, said means being located upon the end of said rod within theconical portion so that the unobstructed cross-sectional area of thepassage through the conical portion and about the means is at least asgreat as the cross-sectional area of the smallest part of the outlet.

2. A signalling device comprising in combination; means providing asound chamber having a fiat Wall with an outlet, said outlet having anenlarged portion and a smaller portion; a flat vibratory body locatedfor movement in close proximity to said wall, means to adjust thevibratory body relative to said wall, said means located in the enlargedportion of said outlet so that the unobstructed cross-sectional area ofpassage between the means and the wall of the enlarged portion is atleast as great as the crosssectional area of the smallest part of theoutlet.

3. A sound signal comprising in combination; a magnet motor, asupporting plate for the same; a clamping collar provided with a Wallsecured to said plate; said Wall having an outlet with an enlargedportion and a smaller portion, a vibrating diaphragm clamped between theplate and the collar to form an air chamber; a projector supported bysaid collar in Said smaller portion and providing the sole inlet andoutlet to said chamber; a disc extending over said enlarged portion andin close proximity thereto, a rod connecting said motor with saiddiaphragm and disc, said rod extending into said enlarged open portionso that the unobstructed cross-sectional area of said enlarged portionaround said rod is at least as great as the cross-sectional area of thesmallest part of the outlet; means for varying the relative position ofsaid disc with respect to said opening; and said motor actuating saiddiaphragm and disc to move air back and forth through said opening.

4. A horn including a housing, a vibratory diaphragm mounted in saidhousing, a motor mechanism connected to said diaphragm to flex the same,said housing being formed with a single orifice therein, comprising bothan inlet and outlet for air and positioned beyond said diaphragm and avalve mechanism controlling the flow of fluid through said outletopening.

5. A horn including a housing, a vibratory diaphragm mounted in saidhousing, a motor mechanism connected to said diaphragm to flex the sameat' acoustical frequencies, said housing being formed with a singleorifice therein, comprising both an inlet and outlet for air andpositioned beyond said diaphragm and a valve mechanism controlling theflow of fluid through said outlet opening.

6. A horn including a housing, a vibratory diaphragm mounted in saidhousing, a motor mechanism connected to said diaphragm to flex the sameat acoustical frequencies, said housing being formed with a singleorifice therein, comprising both an inlet and outlet for air andpositioned beyond said diaphragm, means providing a valve seat, a valvemember cooperating with said seat, one of said elements being associatedwith said orifice and the second of the same being connected to saiddiaphragm.

'7. A horn including a housing, a vibratory diaphragm mounted in saidhousing, a motor mechanism connected to said diaphragm to flex the sameat acoustical frequencies, said housing being formed with a singleorifice therein, comprising both an inlet and outlet for air andpositioned beyond said diaphragm, means providing a valve seat adjacentsaid orifice and a valve connected to said diaphragm and cooperatingwith said seat.

8. A horn including a housing formed with a single opening, comprisingboth an inlet and outlet for air, a disk providing a valve body tocooperate with said opening, a diaphragm mounting said disk and a motorfor flexing said diaphragm at acoustical frequencies.

9. A horn including a housing, a vibratory diaphragm mounted in saidhousing, a motor mechanism connected to said diaphragm to flex the sameat acoustical frequencies, said housing being formed with a singleorifice therein, comprising both an inlet and outlet for air andpositioned beyond said diaphragm, means providing a valve seat adjacentsaid orifice and a valve connected to said diaphragm and cooperatingwith said seat, said valve and seat being normally spaced a distanceless than the normal tendency of movement on the part of said diaphragm.

10. A horn including a housing formed with a single opening, comprisingboth an inlet and outlet for .air, a disk providing a valve body tocooperate with said opening, means for vibrating said disk at acousticalfrequencies and into engagement with the surfaces adjacent said openingand means for shifting said housing with reference to said body to varythe position of the opening relatively thereto.

11. A sound signal comprising in combination, a motor, a trumpet, acollar and'support therefor connected to the motor support forsupporting the trumpet and having a peripheral diaphragm engagingportion, a diaphragm clamped between the edge of the collar and saidmotor and support and movable by the motor, said collar having a secondportion joined to the diaphragm engaging portion and spaced from thesurface of the diaphragm to form a chamber, an actuatable disc supportedfrom the diaphragm in said chamber, so that the major portion of thearea of the face of the disc opposite the diaphragm is in parallelrelation with the said second portion of the collar, and means includingthe motor for thrusting the disc in such close proximity to the collarthat the disc will be substantially in contact with the collar, so thatthe air column in the trumpet is practically stopped.

13. A sound signal comprising, in combination, a motor, a trumpet, aplate having an opening communicatingwith the trumpet and an annularsubstantially flat surface surrounding the opening, means cooperatingwith the said plate to form a sound chamber, a vibratory body operableby the motor within said sound chamber, and having a surface partiallyoverlapping the flat surface of the plate and substantially parallel'thereto, and means normally supporting the vibratory body in such closeproximity to the said flat surface that upon the extreme limit of itsmovement in one direction by said motor it substantially contacts withthe surface to cut ofi the air columnof the trumpet from the soundchamber. 7

ROBERT M. CRI'I'CI-IFIELD.

